Synthetic material sheet for stabilizing coverings

ABSTRACT

The present invention relates to a flexible sheet having a composite structure for stabilizing coatings, comprising a first layer of fiber material and a second layer of fiber material impregnated by a first and a second impregnating material, respectively, and a body layer set between said first layer and said second layer according to a general sandwich structure, where the body layer consists of a third material. The first and the second impregnating materials and the third material constituting the body layer are polymeric materials presenting a substantial affinity, so that the flexible sheet has a physically heterogeneous and chemically homogeneous structure.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to European Patent ApplicationNo. 02425752.9 entitled “Synthetic Material Sheet for StablisingCoverings”, filed Dec. 6, 2002, which is incorporated herein byreference in its entirety.

[0002] 1. Field of the Invention

[0003] The present invention relates to a sheet of synthetic materialfor stabilizing coatings, such as for example floorings or wallcoatings.

[0004] 2. Background Art

[0005] In the laying of a flooring, as in the case of a wall coating, itis necessary for the substrate on which the flooring or wall coating islaid to be as flat as possible. It is moreover advantageous for thecoating—whether this be in the form of a carpet, parquet, marble orceramic tiles, or any other type of material—to be isolated from thesubstrate, the aim being to prevent any infiltration of moisture fromthe substrate itself, which could damage the coating, as well as toobtain a heat-insulating effect, i.e., reducing any heat losses.

[0006] In order to meet the needs outlined above, there have beenavailable on the market for some time now flexible sheets made ofsynthetic material—referred to as stabilizing sheets—which are used asbase for the laying of the coating. Said sheets are principally used forstabilizing floorings, i.e., they are set between the substrate to becoated and the final coating.

[0007] One of such stabilizing sheets is marketed by the presentapplicant under the commercial name EVERLAY and forms the subject of theItalian patent application No. 67797-A/85 in the name of the presentapplicant.

[0008] The sheet EVERLAY consists of a core layer of material made ofsilica-fibers (also commonly referred to as glass fibers) and two layersof plastic material applied on the opposite faces of the core layer.

[0009] This type of product, which has been used and marketed for sometime now, has proved to be altogether satisfactory from the operativeand functional points of view. It is, however, precisely the widespreaduse of this material that has shown that there is still further room forimprovement; for example, as regards release into the environment ofpart of the silica fibers which make up the core layer (there being anincreasing tendency to avoid this kind of phenomenon) and/or as regardsother functional aspects and features of use.

SUMMARY OF THE INVENTION

[0010] The purpose of the present invention is to provide a sheet ofsynthetic material such as to enable the aforesaid improvements.

[0011] According to the invention, the said purpose is achieved thanksto the solution referred to specifically in the ensuing claims.

[0012] In the currently preferred embodiment, the invention relates to aflexible sheet having a composite structure comprising a first layer anda second layer of fiber material impregnated with respectiveimpregnating materials of a substantially polymeric nature and a bodylayer set between the two fiber layers according to a general sandwichstructure, where the body layer also consists of a polymeric material.The polymeric impregnating materials and the body layer present achemical affinity, so that the sheet that forms the subject of thepresent invention is characterized by a chemical homogeneity and aphysical heterogeneity.

[0013] Such a stabilizing sheet preferably envisages that the process ofimpregnation of the fiber material with a polymeric material causes acomplete soaking of the fibers by the polymeric material.

[0014] From this point of view, the solution according to the inventionis clearly distinguished from the solution described in EP-A-0 203 042.In said previous application there is envisaged the presence of a corelayer sandwiched between two layers of fiber material that aregenerically not impregnated and hence designed to provide an overalleffect of strengthening and stiffening: the solution described in EP-A-0203 042 is, in fact, aimed at the production of a coating material madeup of tiles, i.e., a rather rigid one.

[0015] A further advantage of the present invention is provided by thesolidity of the sheet, which is very likely linked to the chemicalhomogeneity of the polymeric materials used—impregnating materials andmaterial constituting the body layer. Albeit without wishing to be tieddown to any theory in this regard, it is reasonable to believe that saidhomogeneity leads to a greater adhesion of the layers to one another,preventing the possibility of a separation of said layers, withconsequent deterioration of said stabilizing sheet.

DESCRIPTION OF THE DRAWINGS

[0016] The invention will now be described, purely by way ofnon-limiting example, with reference to the annexed drawings, in which:

[0017]FIG. 1 is a cross-sectional view of a stabilizing sheet accordingto the invention; and

[0018]FIG. 2 is a schematic representation of the device for productionof the stabilizing sheet according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0019] With reference to FIG. 1, the number 1 designates, as a whole,the stabilizing sheet according to the invention.

[0020] The sheet 1 has a composite structure and comprises two layers 2and 5 made of fiber material, impregnated with respective impregnatingmaterials; set between the layers 2 and 5 is a body layer 3. The fibermaterial is advantageously made of silica fibers or polyester fibers,preferably silica fibers, with random orientation, such as not topresent a direction of prevalent resistance.

[0021] The impregnating materials have preferably the same chemicalcomposition and are made of thermoplastic polymeric materials,preferably chosen in the group made up of polyvinyl chloride (PVC),thermoplastic polyolefins (TPOs) and thermoplastic polyurethanes (TPUs).The impregnating material preferred according to the invention ispolyvinyl chloride.

[0022] According to a preferred embodiment, the impregnating materialsare made of a jellified polymeric material, and even more preferably ofso-called polyvinyl chloride plastisol.

[0023] The body layer 3 consists of a third material, preferably apolymeric material originally in granular form, which assumes a compactstructure via a process of compacting, preferably melting and pressing,so as to create a layer of melted granular material. The material inquestion is preferably a polymeric material, chosen in the group made upof polyvinyl chloride (PVC), thermoplastic polyolefins (TPOs) andthermoplastic polyurethanes (TPUs). The starting granular materialpreferred according to the invention is polyvinyl chloride.

[0024] The body layer 3 has preferably a thickness of less than 2 mm;still more preferably the thickness is approximately 1.5 mm.

[0025] Since the impregnating materials of the fiber layers 2 and 5 andthe third material constituting the body layer 3 are polymeric materialsthat present a substantial affinity/identity, the sheet 1 has astructure that is physically heterogeneous (on account of the presenceof the fiber material of the layers 2 and 5) and chemically homogeneous.

[0026] The chemical homogeneity of these materials leads to a betteradhesion of the layers 2, 3 and 5 between one another, and hence theproduction of a markedly compact structure free from risks of separationof the layers.

[0027] In the embodiment represented in FIG. 1, on the bottom surface 6of the layer 5, i.e., on the surface that is to be set facing thesubstrate to be coated, there is present a further layer 7 made of afoam-structure material, preferably in the form of distinct areolas.Said foam material is preferably polyvinyl chloride foam.

[0028] The function of the layer 7 is to provide a support for the sheet1, a support which further increases the capacity of the sheet 1 forreducing the irregularity of the substrate on which the flooring orcoating is to be laid.

[0029] The sheet 1 may moreover present, on one or on both of thesurfaces 6 and 8 of the fiber layers 5 and 2, respectively, a layer ofadhesive material or glue for facilitating both laying of the sheet 1itself on the substrate to be coated and laying of the flooring or finalcoating on the sheet 1. According to a preferred embodiment, saidadhesive material is present on the surface 8 of the layer 2 and is ahighly tacky glue.

[0030] The sheet 1 may present on the surface 8 of the layer 2 inalternative to the layer of adhesive material a layer of absorbingmaterial intended for absorbing an adhesive material or gluesubsequently applied thereto, in case the adhesive material or gluerequire a substrate in the form of such an absorbing layer for beingemployed. In a preferred embodiment the absorbing material isconstituted by a non-woven textile having a density ranging from about50 to 150 g/m². In another preferred embodiment the absorbing materialpresents non oriented fibers; most preferably the absorbing material isa polyester non-woven textile with non oriented fibers.

[0031]FIG. 2 is a schematic representation of the device for theproduction of the sheet 1.

[0032] On a first production line 21 a—in itself known—there is producedthe first layer 5 of fiber material impregnated with the correspondingimpregnating material. In a parallel way, there is produced—on a secondproduction line 21 b, which is also in itself known—the second layer 2of fiber material impregnated with the corresponding impregnatingmaterial.

[0033] On the first layer 5, which is fed by a conveyor belt 20, a“seeding” device 22 is used for depositing the granules of polymericmaterial that is to constitute the body layer 3. Above the granularlayer thus deposited there is then laid the second layer 2 of fibermaterial.

[0034] At this point the layer 5/granules/layer 2 complex is subjected,inside a device 24, to the joint application of heat and pressure, theaim being to achieve melting of the material in granular formconstituting the body layer 3 and to generate the sandwich structureillustrated in FIG. 1.

[0035] The temperature inside the device 24 is typically approximately165-170° C. at input and approximately 210-220° C. at output.

[0036] The sheet, which has a composite structure, is also subjected(via known pressing means) to a pressure which brings about compactingof the three layers 2, 3 and 5.

[0037] Next, there may be applied to the sheet 1—in a device 25 of aknown type—the layer 7 in foam material with a structure having distinctareolas.

[0038] Also applied to the sheet 1, on one or on both the surfaces 6 and8, there may be a layer of glue, this being performed using the devicedesignated by 26.

[0039] At the end of the production line the sheet 1 is rolled up.

[0040] Of course, the details of implementation and the embodiments maybe amply varied with respect to what is described and illustratedherein, without thereby departing from the scope of the presentinvention, as defined in the annexed claims.

1. A sheet having a composite structure for stabilizing coatings,comprising: a first layer and a second layer, both made of fibermaterial impregnated with a first impregnating material and a secondimpregnating material, respectively; and a body layer set between saidfirst layer and said second layer according to a general sandwichstructure, said body layer being made of a third material; and saidfirst and second impregnating materials and said third materialpresenting a substantial affinity, so that said sheet has a physicallyheterogeneous and chemically homogeneous structure.
 2. The sheetaccording to claim 1, wherein said first and second impregnatingmaterials and said third material presenting a substantial affinity arepolymeric materials comprising polyvinyl chloride, thermoplasticpolyolefins and thermoplastic polyurethanes.
 3. The sheet according toclaim 2, wherein said polymeric materials presenting a substantialaffinity is polyvinyl chloride.
 4. The sheet according to claim 1,wherein said fiber material is silica fiber or polyester fiber.
 5. Thesheet according to claim 1, wherein said first and second impregnatingmaterials is a jellified material.
 6. The sheet according to claim 5,wherein said jellified material is polyvinyl chloride plastisol.
 7. Thesheet according to claim 1, wherein said third material constitutingsaid body layer is a material obtained by compacting of granules.
 8. Thesheet according to claim 1, wherein said body layer has a thickness ofless than 2 mm.
 9. The sheet according to claim 8, wherein said bodylayer has a thickness of approximately 1.5 mm.
 10. The sheet accordingto claim 1, wherein said first layer and said second layer of fibermaterial have respective outer surfaces with respect to the sheet and inthat on at least one of the surfaces there is present a layer of glue.11. The sheet according to claim 10, wherein said glue is present on thetop outer surface in the condition of laying of the sheet.
 12. The sheetaccording to claim 10, wherein said glue is present on the bottom outersurface in the condition of laying of the sheet.
 13. The sheet accordingto claim 10, wherein said glue is of a highly tacky type.
 14. The sheetaccording to claim 1, wherein one between said first layer and saidsecond layer of fiber material has a bottom outer surface in thecondition of laying of the sheet and in that on said bottom outersurface there is present a layer of foam material.
 15. The sheetaccording to claim 14, wherein said layer of foam material is in theform of distinct areolas.
 16. The sheet according to claim 14, whereinsaid layer of foam material consists of polyvinyl chloride foam.
 17. Thesheet according to claim 1, wherein said first layer presents on the topouter surface in the condition of laying of the sheet a layer ofabsorbing material.
 18. The sheet according to claim 17, wherein saidabsorbing material is constituted by a non-woven textile.
 19. The sheetaccording to claim 17, wherein said absorbing material presents adensity ranging from about 50 to 150 g/m².
 20. The sheet according toclaim 18, wherein said non-woven textile presents non oriented fibers.21. The sheet according to claim 17, wherein said absorbing material isa polyester non-woven textile.
 22. A process of making a composite sheetcomprising the steps of: impregnating a first layer of fiber materialwith a first impregnating material, said first layer having a firstsurface and a second surface, said first surface being the top outersurface with respect to the composite sheet, and said second surfacefacing a body layer; impregnating a second layer of fiber material witha second impregnating material, said second layer having a third surfaceand a forth surface, said third surface facing the body layer, and saidforth surface being the bottom outer surface with respect to thecomposite sheet; depositing, on the third surface of the second layer, alayer of a third material to form the body layer; placing the secondlayer atop the body layer, thereby forming a composite having said bodylayer set in between said first layer and said second layer according toa general sandwich structure; heating the composite to allow the bodylayer to melt; and pressing the composite.
 23. The process according toclaim 22 wherein said first layer is impregnated by soaking of saidfirst layer by said first impregnating material and said second layer isimpregnated by soaking of said second layer by said second impregnatingmaterial.
 24. The process according to claim 22 wherein said compositeis heated to about 165-170° C. at input and about 210-220° C. at output.25. The process according to claim 22 wherein said composite issubjected to pressure which results in the compacting of said first,second and said body layers.
 26. The process according to claim 22wherein said third material is a granular material.
 27. The processaccording to claim 22 wherein said first, second impregnating materialsand said third material comprise polyvinyl chloride, thermoplasticpolyolefins and thermoplastic polyurethanes.
 28. The process accordingto claim 27 wherein said first, second impregnating materials and saidthird material are each polyvinyl chloride.
 29. The process according toclaim 22 wherein said first and second impregnating materials arejellified polymeric material.
 30. The process according to claim 29wherein said jellified material is polyvinyl chloride plastisol.
 31. Theprocess according to claim 22 further comprising the step of affixingdistinct areolas of foam structure material to the bottom outer surfacewith respect to the composite.
 32. The process according to claim 31wherein the foam structure material is polyvinyl chloride foam.
 33. Theprocess according to claim 22 further comprising the step of applying alayer of adhesive material to the top and/or bottom outer surfaces ofthe composite sheet.
 35. The process according to claim 22 furthercomprising the step of affixing a layer of absorbing material to the topouter surface of the composite.